*{
    margin: 0;
    height: 0;
}
body{
    width: 100vw;
    height: 100vh;
}

.item{
    width: 100%;
    height: 100%;
}

html[data-theme='light'] .item{
    background-color: #fff;
    color: #000;
}
html[data-theme='dark'] .item{
    background-color: #000;
    color: #fff;
}